Yet they all exist in the 92,000-acre park that straddles Tucson like saddlebags. Elevation within the two-part park (Tucson Mountain District on the west, Rincon Mountain District on the east - commonly just called west side and east side) ranges from about 2,300 feet on the west side to 8,482 feet at the summit of Rincon Peak on the east side.

For the math-impaired, that's more than 6,000 vertical feet.

By comparison, the Grand Canyon ranges from about 2,400 feet at the Colorado River (in the Phantom Ranch area) to about 8,200 feet at the North Rim.

Thanks to such an extreme elevation, Saguaro National Park is home to more than 1,700 species of plants and animals, making it one of the most biologically diverse parks in the country.

Visitors, especially those from out of state, are struck by two things, according to chief ranger Bob Love.

"The enormity of the saguaro cactus," he said. "It's just a magical figure. The other is the lushness of this desert."

That lushness is due mostly to the fact that the Sonoran Desert, unlike most others, experiences two rainy seasons. But it's the saguaros that draw the oohs and aahs from out-of-state visitors.

"The saguaro is sort of the icon of the American Southwest," said Sarah Craighead, superintendent of the park. "You see it in every Western movie, it's on Mexican food signs, it's such a recognizable plant. Part of it, too, is that people are drawn to it because it looks like a person."

The park was ranked No. 3 on a list, compiled by the Arizona Office of Tourism, of the most visited natural attractions in the state for 2007, the last complete year for which numbers are available. Only the Grand Canyon and South Mountain Park attracted more visitors.

Variety of attractions

The park is drop-dead gorgeous, luring hikers, photographers and naturalists of all stripes, along with the curious or those just looking for a scenic drive.

Hikers appreciate the miles of trails, most of which are open to equestrians. Although there is only one short trail for mountain bikers, street cyclists flock to the east side of the park to ride Cactus Forest Drive, 8 miles of twists and dips and turns and hills.

Each district has its own visitor center, where guests can learn about the park's plants and animals, geology and archaeology, ranger-led events and interpretive activities.

The busy season at Saguaro runs from about November through mid-April. During that time, rangers and volunteers present a number of interpretive programs each day.

There are no RV campgrounds in the park. Backcountry camping is permitted only in east district, and the minimum hike to reach a backcountry campsite is 6 miles one way, cautioned ranger Jeff Wallner.

When people ask him what there is to do at the park, Wallner's answer is simple: "Take a drive and take a walk. Those are the two things that really get you most in touch with this place."

Few things compare with a walk through the Sonoran Desert, he said.

"It's like walking through nature's garden, but you get the same feeling as you get in a (manmade) garden - a kind of peace and tranquility."

Perfect for photos

The park seems tailor-made for photographers seeking great sunset photos, especially on the west side.

"Because we face the west, you can pick out the saguaro you want as a silhouette in your picture and just wait for sunset," said ranger Philip Brown.

Sunset is indeed a magical time at the park. Shadows grow long while the west-facing hillsides take on a deep, cuprous glow. Everything seems sharp and clean in this light, and there's a sense of something wonderful to come.

The saguaros are especially evocative in the warm glow of early morning or late afternoon. Their upraised arms seem to welcome the rising sun, or to bid goodbye to the setting sun.

It's striking.

"Most people aren't used to seeing a landscape that looks like this," Brown said. "This is unique to this part of the world, and if you're from New Jersey or South Carolina or Minnesota, this is totally alien-looking. And we've preserved a big piece of it here so it will always be available for people to come and study and enjoy.

"We're preserving a piece of America as it has always been."

Hiker's paradise

The park boasts about 170 miles of hiking trails, many of which begin right off the scenic drives.

Jim and Barb Young, full time RVers who volunteer at Casa Grande National Monument during the winter, were hiking the Mica View Trail on a weekend last fall. They visit often.

"We just like the desert," Barb said. "It's beautiful. And quiet, away from traffic."

Jim noted the variety of trails, especially in the northwestern section of the Rincon Mountain District.

"There's a trail you can do no matter how much time you have or what sort of (fitness) level you're at," he said. "And all of them give you a good look at the Sonoran Desert."

The desert is a place where you can get away from it all and reflect on your life. It can be a place that fosters communication.

"We do a lot of talking on the trail," Barb said.

Gary and Sandi Bonesteel of Green Valley were hiking the Loma Verde Trail in the Rincon district. They visit regularly for exercise and "just to get away."

They also hike the trails that crisscross the northwestern corner of the Rincon district.

"What makes this park so nice is it's close to Tucson," Gary said. "The average person can utilize it for an afternoon."

"We need places like this to escape," Sandi said. "It's good for the soul."

Also hiking the Loma Verde Trail, even though there was a sign at the trailhead warning that mountain lions had been spotted in the area, were University of Arizona wildlife biology students Tim and Rosa Jessen and Jessica Gwinn. Like the Bonesteels, the group was undeterred by the sign.

"If we see a mountain lion, that would be cool," Rosa said.

"Visiting the park gives you an appreciation for the things you can see outside the city," Tim said. "If you enjoy nature and the outdoors, the park is a great place. And no matter where you are in Tucson, it's not too far to go."

More than 70 percent of the park is designated wilderness, places where visitors can experience what the area was like 100 or 200 or 1,000 years ago.

"The only imprint of man they're going to see are trails," Love said.

Even in non-wilderness areas, if you venture out on a trail you'll likely find a place where all traces of the outside world vanish. There are no houses, no roads, no power lines.

Marie Schneider and her husband, Phil Mizell, were pondering the petroglyphs at Signal Hill in the Tucson Mountain District.

"It's so magic here," said Schneider, who had recently moved to the area from Washington. "We just expected sandy desert."

"Natural places are part of what we are," Mizell said. "If you live in a city, in front of a TV, you can forget that.

"But when you come out to a place like this you remember that part of your life."

Saguaro National Park

GETTING THERE The Rincon Mountain District is the east side of the park. From central Phoenix, take Interstate 10 east to Tucson. Exit at Houghton Road (Exit 275) and go 9.5 miles north to Old Spanish Trail and turn right. G 3 miles southeast to the park entrance on the left side of the road.

The Tucson Mountain District is the west side of the park. Take Interstate 10 east toward Tucson and get off at Avra Valley Road (Exit 242). Go 5 miles west on Avra Valley Road to Sandario Road and turn left (south). Go 9 miles to Kinney Road and turn left (east). The visitor center is 2 miles ahead on the left

ADMISSION $10 per vehicle, $5 if on a bicycle or on foot. Fee is good for both districts for seven days. A Saguaro National Park Annual Pass costs $25. An Interagency Annual Pass, good at all national parks and monuments, costs $80.

Things to do

You could spend months exploring Saguaro National Park and not see it all. Here are a few ideas to give you a taste of the area:

RINCON MOUNTAIN DISTRICT
• Cactus Forest Drive. There is no finer introduction to the park than this scenic drive. The entire route is paved, and nearly all of it is one-way. The road twists and turns, making an 8-mile loop, all the while providing expansive views of mountain ranges and rolling hills of creosote, ocotillo, prickly pear, brittle bush, cholla, mesquite, paloverde and saguaro. There are picnic areas and trailheads just off the drive. Watch out for cyclists who flock to the road, especially on weekends.

• Desert Ecology Trail. This walk, just off Cactus Forest Drive, is a paved, fairly level loop with lots of signs describing desert plants and animals. It only takes about 10 minutes to walk the trail.

TUCSON MOUNTAIN DISTRICT

• Signal Peak Picnic Area. A short trail leads to the top of the hill, where you'll find an assortment of ancient rock art. The petroglyphs consist of humanoid stick figures, highly stylized animals and abstract geometric shapes. What do they mean? Your guess is as good as any.

• King Canyon Trail. This is one of chief ranger Bob Love's favorite hikes. The trail follows a scenic wash past the historical Mam-A-Gah Picnic Area.

• Wasson Peak. This is the hike Love encourages all visitors - if they're fit enough - to make. At 4,687 feet, Wasson Peak is the highest point in the Tucson Mountain District. "You get this tremendous 360-degree view of not only the Tucson metro area and the Catalina Mountains and Rincon Mountains to the east, but the Avra Valley and the Baboquivaris to the west. It's an unbelievable view."